Today’s post is a blurb from Paul Ehrlich on the human population problem for conservation of biodiversity.

The size of the human population is approaching 7 billion people, and its most fundamental connection with conservation is simple: people compete with other animals., which unlike green plants cannot make their own food. At present Homo sapiens uses, coopts, or destroys close to half of all the food available to the rest of the animal kingdom. That means that, in essence, every human being added to the population means fewer individuals can be supported in the remaining fauna.

But human population growth does much more than simply cause a proportional decline in animal biodiversity – since as you know, we degrade nature in many ways besides competing with animals for food. Each additional person will have a disproportionate negative impact on biodiversity in general. The first farmers started farming the richest soils they could find and utilised the richest and most accessible resources first (Ehrlich & Ehrlich 2005). Now much of the soil that people first farmed has been eroded away or paved over, and agriculturalists increasingly are forced to turn to marginal land to grow more food.

The tasks of conservation biologists are made more difficult by human population growth, as is readily seen in the I=PAT equation (Holdren & Ehrlich 1974; Ehrlich & Ehrlich 1981). Impact (I) on biodiversity is not only a result of population size (P), but of that size multiplied by affluence (A) measured as per capita consumption, and that product multiplied by another factor (T), which summarises the technologies and socio-political-economic arrangements to service that consumption. More people surrounding a rainforest reserve in a poor nation often means more individuals invading the reserve to gather firewood or bush meat. More poeple in a rich country may mean more off-road vehicles (ORVs) assulting the biota – especially if the ORV manufacturers are politically powerful and can succesfully fight bans on their use. As poor countries’ populations grow and segments of them become more affluent, demand rises for meat and automobiles, with domesticated animals competing with or devouring native biota, cars causing all sorts of assults on biodiversity, and both adding to climate disruption. Globally, as a growing population demands greater quantities of plastics, industrial chemicals, pesticides, fertilisers, cosmetics, and medicines, the toxification of the planet escalates, bringing frightening problems for organisms ranging from polar bears to frogs (to say nothing of people!).

In sum, population growth (along with escalating consumption and the use of environmentally malign technologies) is a major driver of the ongoing destruction of populations, species, and communities that is a salient feature of the Anthropocene. Humanity , as the dominant animal (Ehrlich & Ehrlich 2008), simply out competes other animals for the planet’s productivity, and often both plants and animals for its freshwater. While dealing with more limited problems, it therefore behoves every conservation biologist to put part of her time into restraining those drivers, including working to humanely lower [sic] birth rates until population growth stops and begins a slow decline twoard a sustainable size (Daily et al. 1994).

Incidentally, Paul Ehrlich is travelling to Adelaide this year (November 2010) for some high-profile talks and meetings. Stay tuned for coverage of the events.

People? 335 million tonnes of liveweight, Livestock? 700 million tonnes.
22 million hectares of crop land produce many (5 to 10) times more food
than the 380 million which are grazed, trampled and
degraded … with plenty burned as well. 12 percent of what we (globally) coopt
provides 83 percent of our food while the 58 percent co-opted by
livestock provides … eventually … 17 percent. We can pretty well halve
our impact on the planet by changing diet. But plenty of people
don’t think the planet is worth such a change. Fancy
replacing that 17 percent with the same stuff that provides the other
83 percent? Of course for some individuals their diet ratios are a
little different so the change is bigger. BBQs easily trump any faux concern
for the planet.

The I=PAT equation seems reasonable, but it does not take into account reproduction rates. It seems that population growth rates are relatively low in affluent societies and high for those in poverty. An important question is whether providing the carbon-free nuclear energy would be able to produce the affluence to reduce the world population growth without increasing the impact. Technology has the potential to also increase the effectiveness of recycling and resource recovery, which could reduce the impact per person. I am interested in finding out any opinions on this?

In South Australia, our government claims to be able to produce desalinated water and be carbon neutral in the process, yet they have a high population growth target that eclipses any savings by using renewable energy. The population target is short-sighted and irresponsible and seems to suit the business interests that provide political donations that drive our political parties. Political parties should be rejected by the electorate and we should vote for representatives in electorates that are interested in real people rather than narrow business interests. We cannot afford to have government and opposition parties working against each other. We all need to work together to solve the challenges of the new few decades and beyond.

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